One area of interest in the police search has been the Oak Road playing fields in the city, with officers returning on Tuesday and using power tools to cut back undergrowth.

On Wednesday, divers carried out further searches in a pond at the location.

Image caption
Police divers returned to Oak Road pond in Hull on Wednesday for further searches

Humberside Police said hundreds of uniformed officers and around 50 detectives have been searching "around the clock" for Libby, with specialist search advisors, underwater officers, the fire service, police dogs, local businesses and the public also involved.

The force said: "Our priority remains to find Libby and support her family at this incredibly distressing time."

Officers have posted letters to people living near to Raglan Street asking if anyone heard "anything unusual" on the night of her disappearance.

The force said it had "received hundreds of calls" and was pursuing a number of lines of inquiry.

On the night of her disappearance, detectives think Ms Squire arrived at her student house at about 23:30, where her mobile phone was found.

They do not believe she entered the house and said her phone "has not provided any further insight as to her movements that night".

She was spotted on CCTV 10 minutes later near a bench on Beverley Road, where it is thought a motorist stopped to offer her help.

She is believed to have been in the area for about 30 minutes.

A 24-year-old man arrested on suspicion of abduction remains a person of interest, police said.